I have found these strikingly marked caterpillars feeding on sallow, they also feed on a variety of trees and shrubs including birch and hawthorn. Easily recognizable with a white stripe along the side, above this it has patches of red patches on black squares. And a yellow stripe along its back with a hump on its front and a smaller hump on its rear. For defense against predators, the larvae have striking colours, fine long hairs and the larvae can raise the front horn with its head curled under its body. The moth gets its name from the black dagger markings on its forewings.